2D dynamic array using ArrayList in Java

Question

I need to implement a 2D dynamic array. The number of rows is fixed, say n. But the number of columns for each row is not fixed and equivalent. For instance, the first row h

Answer 1

How about List> ?

For Example:

List> list = new ArrayList>();

List row1 = new ArrayList();
row1.add(new Foo());
row1.add(new Foo());
row1.add(new Foo());
list.add(row1);

List row2 = new ArrayList();
row2.add(new Foo());
row2.add(new Foo());

list.add(row2);